Process for preparing isoxaflutole

Abstract

A process for preparing isoxaflutole of formula (I) wherein the process comprises: admixing (5-cyclopropyl-4-isoxazolyl)[2-(methylthio)-4-(trifluoromethyl)phenyl]-methanone of formula (II) with acetic acid, acetic anhydride and hydrogen peroxide in the presence of a strong acid.

What is claimed is: 
     
       1. A process for preparing isoxaflutole of formula (I) 
       
         
           
           
               
               
           
         
       
       wherein the process comprises:
 admixing the compound of formula (II) 
 
       
         
           
           
               
               
           
         
       
       with acetic acid, acetic anhydride, and hydrogen peroxide in the presence of a strong acid. 
     
     
       2. The process of  claim 1 , further comprising quenching the reaction mixture; isolating the compound of formula (I); and optionally purifying the obtained compound of formula (I). 
     
     
       3. The process of  claim 1 , wherein the molar ratio between the hydrogen peroxide and the compound of formula (II) is from about 10:1 to about 1:1. 
     
     
       4. The process of  claim 3 , wherein the molar ratio between the hydrogen peroxide and the compound of formula (II) is about 5.5:1. 
     
     
       5. The process of  claim 1 , wherein the process is carried out in an organic solvent selected from monochlorobenzene, polychlorobenzene, toluene, xylene, ethyl acetate, butyl acetate, acetonitrile, N-methylpyrrolidone (NMP) and dimethylacetamide (N,N-DMA), acetone, methanol, ethanol, or a combination thereof. 
     
     
       6. The process of  claim 1 , wherein said strong acid is selected from sulfuric acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, hydrochloric acid, nitric acid or a combination thereof. 
     
     
       7. The process of  claim 6 , wherein the molar ratio between the strong acid and the compound of formula (II) is from about 1:1 to about 1:100. 
     
     
       8. The process of  claim 1 , wherein said strong acid is sulfuric acid. 
     
     
       9. The process of  claim 8 , wherein the molar ratio between the sulfuric acid and the compound of formula (II) is from about 1:1 to about 1:100. 
     
     
       10. The process of  claim 8 , wherein the molar ratio between the sulfuric acid and the compound of formula (II) is about 1:3.5. 
     
     
       11. The process of  claim 8 , wherein the molar ratio between the sulfuric acid and the compound of formula (II) is about 1:2.2. 
     
     
       12. The process of  claim 1 , wherein the process is conducted at a temperature ranging from about 25° C. to about 100° C. 
     
     
       13. The process of  claim 12  wherein said strong acid is selected from sulfuric acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, hydrochloric acid, nitric acid or a combination thereof. 
     
     
       14. The process of  claim 12 , wherein the molar ratio between the strong acid and the compound of formula (II) is from about 1:1 to about 1:100. 
     
     
       15. The process of  claim 12 , wherein said strong acid is sulfuric acid. 
     
     
       16. The process of  claim 12 , wherein the molar ratio between the sulfuric acid and the compound of formula (II) is about 1:2.2. 
     
     
       17. The process of  claim 12 , wherein the molar ratio between the hydrogen peroxide and the compound of formula (II) is from about 10:1 to about 1:1. 
     
     
       18. The process of  claim 12 , wherein the process is carried out in an organic solvent selected from monochlorobenzene, polychlorobenzene, toluene, xylene, ethyl acetate, butyl acetate, acetonitrile, N-methylpyrrolidone (NMP) and dimethylacetamide (N,N-DMA), acetone, methanol, ethanol, or a combination thereof. 
     
     
       19. The process of  claim 8 , wherein the process is conducted at a temperature ranging from about 25° C. to about 100° C.